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pam_otpw: verify one-time passwords

pam_otpw - verify one-time passwords
pam_otpw [ arguments ]


OTPW is a one-time password authentication system. It compares entered passwords with hash values stored in the user's home directory in the file ~/.otpw. Once a password was entered correctly, its hash value in ~/.otpw will be overwritten with hyphens, which disables its use in future authentication. A lock file ~/.otpw.lock prevents that the same password challenge is issued on several concurrent authentication sessions. This helps to prevent an eavesdropper from copying a one-time password as it is entered instantly into a second session, in the hope to get access by sending the final newline character faster than the user could. Both an authentication management and a session management function are offered by this module. The authentication function asks for and verifies one-time passwords. The session function prints a message after login that reminds the user of the remaining number of one-time passwords.


debug Turn on debugging via syslog(3). nolock Disable locking. This option tells the authentication function of pam_otpw.so to ignore any existing ~/.otpw.lock lock file and not to generate any. With this option, pam_otpw.so will never ask for several passwords simultaneously.


The OTPW package, which includes the otpw-gen progam, has been developed by Markus Kuhn. The most recent version is available from <//www.cl.cam.ac.uk/~mgk25/otpw.html>.


otpw-gen(1), pam(8) 2003-09-30 PAMOTPW(8) PAM_OTPW(8)

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